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R Y Dodd

Publications and source records attributed to R Y Dodd.

At least 91 records · Page 5Linked to original sources
PubMed1982

Proficiency in testing for hepatitis B surface antigen: experience with Ausria II.

Eight hepatitis B surface antigen (HBsAg) proficiency panels were tested using a radioimmunoassay (RIA) test kit during 1978 and 1979 by routine processing laboratories within the 57 American Red Cross Blood Services Regions. The test results were analyzed and it was found that lot-to-lot variability in the reagents may result in a measurable loss of sensitivity of the test leading to an increased error rate. On the basis of these studies, it is recommended that the positive to negative (P/N) ratio for validation of the test be raised to at least 25.

Analysis of Variance↗
PubMed1981

A modified technique for the detection of hepatitis B virus-specific DNA polymerase.

A modified and improved technique for the detection of hepatitis B virus-specific DNA polymerase activity is described. DNA polymerase is released from Dane particles by mixing samples with the detergent Nonidet P-40 and beta-mercaptoethanol. After incubation of pretreated samples with a reaction mixture containing tritiated thymidine-methyl-5'-triphosphate (3H-TTP), DNA is precipitated onto a trichloroacetic acid (TCA)-treated paper. Unincorporated 3H-TTP is then chromatographically eluted with a 5% TCA solution and precipitated counts are determined. A sample is considered positive for DNA polymerase if the incorporated counts are significantly higher than the counts of a group of negative control samples. The modifications include pretreatment of the paper with TCA, chromatographic elution of unincorporated 3H-TTP with TCA solution, prefiltration of the sample through bacteriological filters, and use of sound statistical methods for evaluation of data. These changes have led to a highly reproducible, reliable and sensitive technique. The coefficient of variation of negative control samples from various test runs was in the range of 2.7-8.5%. A linear relationship between incorporated counts and DNA polymerase concentration was shown. A total of 419 serum samples from asymptomatic HBsAg-carrying blood donors were tested. Twenty-three (5.5%) of these were found to contain detectable DNA polymerase activity. All 23 samples also contained HBeAg.

Chemical Precipitation↗
PubMed1981

Comparative evaluation of radioimmunoassay kits used for testing blood for hepatitis B surface antigen.

A comparative evaluation of six licensed radioimmunoassay kits for the detection of hepatitis B surface antigen (HBsAg) has been performed. Each method met the federal licensure requirements for the test. The performance of the kits varied considerably, however, when they were challenged to the limits of their sensitivities. During the period December 1978 through March 1979, four kits were judged to be of equivalent high sensitivity, whereas two were less sensitive. Three of the kits, including two of those with high sensitivity, generated a high (6%--7%) proportion of false reactive results. The sensitivities of all kits decreased during the shelf lives of the reagents.

Evaluation Studies as Topic↗
PubMed1980

Hepatitis-associated markers in the American Red Cross volunteer blood donor population. I. Trends in HBsAg detection, 1975--1978.

From January 1975 to December 1978, 19,140,169 units of blood were collected by the American Red Cross at 57 regional locations. Each unit was tested for hepatitis B surface antigen (HBsAg) by a single commercial radioimmunoassay test system. A total of 15,954 donations were reported reactive, representing a rate of HBsAg reactivity of 0.83/1,000 units tested. The rate during 1975 was 0.94/1,000 units tested, decreasing to 0.71/1,000 units tested in 1978 (p < 0.005). The prevalence of HBsAg among first-time donors was 2.08/1,000 during 1977 and 1978, 2.7 times higher than that calculated for repeat donors (0.77/1,000 donors). Substantial geographic variation in the prevalence and rate of detection of HBsAg was observed.

Blood Donors↗
PubMed1980

Hepatitis-associated markers in the American Red Cross volunteer blood donor population. ii. Distribution of level of HBsAg reactivity by radioimmunoassay and occurrence of nonspecific reactivity.

During the year 1978 this laboratory evaluated the specificity of all samples found reactive for hepatitis B surface antigen (HBsAg) by 44 of 57 regions of the American Red Cross Blood Services. Radioimmunoassay detected a total of 1.921 HBsAg-reactive sampled among more than three million donor units tested. A vast majority (96%) of the samples had high level of HBsAg (greater than or equal to 20 ng/ml). Only about 50% of the samples with low level of HBsAg (less than 20 ng/ml) were reactive in reversed passive hemagglutination. There were 13 samples that were repeatable for HBsAg but were considered nonspecific as they were nonneutralizable in radioimmunoassay, 2 donors who showed nonspecific reactivity were further tested and it was found that the reactivity in radioimmunoassay persisted for more than 9 months, and this reactivity was also detectable by a second commercial kit for HBsAg. Antibodies to core and surface antigen were not found in any of the nine samples that were tested. The explanation of this nonspecific reactivity is unclear, but the data suggest that the nonspecific factor(s) may be an inherent property of the sample rather than a deficiency of the test reagents.

Antibody Specificity↗
PubMed1980

Hepatitis-associated with markers in the American Red Cross volunteer blood donor population. III. Influence of donor selection practice upon HBsAg prevalence.

The American Red Cross collects blood from a number of defined subsets of the donor population and teh proportion of blood collected from each subset varies widely from center to center. A large part of the variation in prevalence of HBsAg may be related to variations in the proportion of blood collected from plants and factories, military units and schools or colleges. We have derived a regression equation, significant at the p less than 0.001 level, which links HBsAg prevalence with these collection parameters. Using this equation, we were able to predict the prevelance of HBsAg among first-time donors in 6 of the 9 geographic divisions of the United States with an accuracy exceeding 10%. The predictions for the remaining division were within 35% of the actual value. Correlation studies were supported by measurements of true donor prevalence in three blood centers.

Blood Donors↗
PubMed1978

A highly sensitive radioimmunoassay technique for subtyping the antibody to hepatitis B surface antigen.

A highly sensitive technique for determining the subtype specificity of antibody to hepatitis B surface antigen (anti-HBs) is described. Immunoadsorbent consisting of controlled pore glass coated with subtype specific HBsAg was used to remove homologous antibody from the test samples before testing them for residual antibody by a commercially available radioimmunoassay (RIA). A total of 73 anti-HBs-positive samples from asymptomatic blood donors were tested. In nearly 80% of these samples the subtype reactivity could be determined by this technique. Only 67% could be typed by conventional liquid phase absorption RIA and 22% by passive hemagglutination inhibition techniques. Among the samples with low anti-HBs titer, ad and ay subtypes were found with equal frequency; however, with the increase in anti-HBs titer, considerably higher proportion of ad specificity was detected.

Antibodies, Viral↗
PubMed1978

A novel immunoadsorbent: use for the preparation of monospecific antibodies to the hepatitis B antigen.

Controlled pore glass (CPG) adsorbs hepatitis B surface antigen (HBsAg) from whole plasma with a high degree of specificity. The resultant complex is stable at acid pH and in the presence of high concentrations of sodium thiocyanate. The adsorbed HBsAg is qualitatively and quantitatively similar to the soluble material in its ability to bind antibodies to HBsAg (anti-HBs). The HBsAg in 1 ml of strongly reactive plasma is adsorbed by 100 mg of CPG, which can then specifically bind 32,000 passive hemagglutination units of anti-HBs. Bound antibody can be eluted in 77% yield by acid or by chaotropic ions and the CPG-HBsAg complex can be reused in further adsorption-elution cycles. Antibody to HBsAg can be purified 144-fold in a single step by using this technique. The preparation of monospecific subtyping reagents for HBsAg and of immunochemically purified anti-HBs is described.

Adsorption↗
PubMed1978

Relationship of subtypes of hepatitis B surface antigen with e antigen and its corresponding antibody.

A total of 3,212 samples of blood from asymptomatic volunteer donors positive for hepatitis B surface antigen (HBsAg) by radioimmunoassay and 860 samples negative for HBsAg were tested for the presence of hepatitis e antigen (HBeAg) and its corresponding antibody (anti-HBe) using a rheophoresis technique. Neither HBeAg nor anti-HBe was detected in any sample negative for HBsAg. Of the HBsAg-positive samples, 237 (7.4%) contained HBeAg and 749 (23.3%) had anti-HBe. HBeAg was significantly (P less than or equal to 0.0005) more likely to be in samples with high titers of HBsAg. Anti-HBe had an equal chance of occurring in samples with low or high titers of HBsAg. Both HBeAg and anti-HBe were found in samples with HBsAg subtypes ad or ay. However, a significant association (P less than or equal to 0.0005) between HBsAg/ay and HBeAg as well as an association between anti-HBe and HBsAg/ad was found.

Antibodies, Viral↗
PubMed1976

Gel filtration of hepatitis B surface antigen: increased size of the native particle.

The Stokes radius of umpurified hepatitis B antigen (HBSAg) was determined by chromatography on a carefully calibrated Sepharose 4B column. A value of 14-2 nm was found by this procedure, contrasting with a published value of II nm for purified, pepsin-treated HBSAg. Chromatography at pH 3 appeared to reduce the Strokes radius of HBSAg to II nm. Evidence is presented to show that serum proteins adsorbed to HBSAg can be removed with pepsin or acid.

Blood Proteins↗
PubMed1975

Hepatitis B (surface) antigen testing by radioimmunoassaymexperience in a very large volunteer donor population.

The results of hepatitis B surface antigen (HBs-Ag) testing in a large volunteer blood donor population are described. Counterelectrophoresis and three versions of solid-phase radioimmunoassay technic are compared and evaluated. Initial results suggested that the radioimmunoassay technic are compared and evaluated. Initial results suggested that the radioimmunoassay technic detected more than five times as many reactive donors as did counterelectrophoresis. The specificity of the radioimmunoassay technic has been increased by successive modifications, and recent results show that the technic detects 73 percent more reactive donors than does counterelectrophoresis. Not all of these reactions are specific, and it is estimated that the true gain in detection of HBsAg carriers is 49 percent of the value found by counterelectroesis. The incidence of HBsAg carriers in the America Red Cross donor population is about 1.25 per 1,000.

Blood Donors↗
PubMed1975

Hepatitis B core antigen. Detection of antibody by radioimmunoprecipitation.

Radioactive cores were prepared from concentrated Dane particles by DNA polymerase reaction followed by CsCl density gradient centrifugation. Two radioactive peaks were obtained: one peak with an average density of 1.36 g/cm-3 in CsCl contained cores that possessed full serologic reactivity; the other peak, with a density of 1.28 to 1.32 g/cm-3, contained cores associated with globulin. A double antibody immunoprecipitation test was developed, using the radioactive heavy cores as a source of antigen. The test was at least 300 times as sensitive as complement fixation for detecting antibody to core.

Animals↗